There are four major types of mechanical humidifiers. Steam humidifiers boil water and release the warm steam into a room. Impeller humidifiers utilize a fast rotating disk in combination with a comb to first liberate large droplets of water and then break the droplets into smaller diffusible droplets that are introduced into the room. Evaporative systems use a wick that in positioned in a water source. The water migrated along the wick by capillary action and evaporates into the air. A blower may be used to increase the rate of evaporation. Ultrasonic humidifiers use a submerged, vibrating metal diaphragm or ultrasonic board to impart mechanical energy to the water. The use of ultrasonic energy results in the formation of an atomized mist above the surface of the reservoir.
In ultrasonic humidifiers, an electronic component called a transducer which is capable of transforming electrical energy into mechanical energy for generating a cool mist is used. More specifically, the transducer includes a vibrating part called a nebulizer which vibrates quietly at greater than 1.5 million times per second in order to convert water into a fine, cool mist. Humidifiers using a nebulizer for generating a cool mist are more commonly referred to as ultrasonic humidifiers and are the latest advance in the humidifier field.
Ultrasonic humidifiers usually incorporate a removable water tank or container for holding a supply of water. The tank contains a valve which controls the flow of water from the tank into a reservoir at the bottom of the humidifier. The nebulizer for churning the water into a fine, cool mist is usually located at the bottom of the reservoir. When the water tank is fully or partly empty it is simply lifted out, taken to a source of water such as a water faucet, refilled and then returned for subsequent use.
Ultrasonic humidifier technology has been used in humidifier products in the consumer market for several years. When this technology was first introduced it was a big success in the US market. Retailers and customers were impressed by the visible mist that was emitted from these units, they were safe to use, yet they were cool-to-the-touch.
After several years on the market the problems of the ultrasonic humidifiers became known to the public, and the sales of these humidifiers all but died. The major problem was “White Dust”. This occurs during the evaporation process, (changing from a liquid to a gas) this happens after the mist (micro-droplets of water) leaves the unit and evaporates in the air, allowing small amounts of water born contaminants (primarily calcium) to drop to the floor, and ultimately creating a dusty white coating on horizontal surfaces.
A resurgence of ultrasonic humidifiers slowly started again with the added use of a mineral filtration cartridge to remove contaminants from the water before they become air-borne. This also reduced the contamination build-up on the transducer disks that create the ultrasonic action. This also helped reduced some of the cleaning requirements of the ultrasonic transducer disk.
Additionally, in the last several years, manufacturers have also added a method to warm the ultrasonic mist, with a heating device that warms the water before the ultrasonic atomization. This has allowed for consumers, with the flip of a switch, to choose between cool or warm ultrasonic humidification.
The method used to evacuate the atomized micro droplets of water from the typical ultrasonic humidifier is to use a small blower fan, blowing the droplets out of the unit to be dispersed into the room. This method is effective but does not allow for any whole-room disbursement of the vapors. The water droplets tend to just spew out a few feet and then drop to the floor as they evaporate. Accordingly, there is a need for an ultrasonic humidifier that more efficiently disperses humidity throughout a room.